Possible Clues:

• All you can carry
• Tailor-made with no tie - is that as much as one can handle?
• Two bags of groceries, say
• Laundry unit
• Amount you can carry
• As much as one can carry
• Twelve books, maybe
• As much as one may carry
• Milk, oddly in a way, is as much as one can bear
• All one can carry